Blowout device for electric switches



May 6, 1941.

"r. B. JOCHEM ETAL 2,240,654 BLOWOUT DEVICE FOR ELECTRIC SWITCHES Filed July 2, 1938 2 Sheets-Sheet l Patented May 6, 1941 [Pheodorelt Jochem and Clarence W.- Kuhn.

Wauwatosa, and William 0. Stevens, Milwaukee, Win, assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application July 2, 1938, Serial No. 217,194

6 Claims.

This invention relates to magnetic blowout devices for electric switches.

The invention relates more particularly to magnetic blowout devices in which the are formed upon opening of the switch contacts is transferred to spaced arc dissipating elements to extinguish the same.

The invention has among its objects to provide a rugged and efllclent blowout device of the aforesaid character which is of improved con-' struction and can be readily manufactured at low cost.

- Another object is to provide a blowout device of the aforesaid character including an arc chute which can be; readily removed to permit inspection or repair of the switch contacts or parts of the blowout device.

Another object is to provide a blowout device having arc dissipating elements which are of heavy section and of high thermal conductivity to eflect rapid cooling of the arc.

Various other objects and advantages of the invention will hereinafter appear. v The accompanying drawings illustrate an embodimentof the invention which will now be described, it being understood that various modiiications may be made in the embodiment illustrated without departing from the spirit and scope of the appended claims.

In the drawings- Figure l is a side elevational view of a switch having a blowout device embodying the invention associated therewith;

Fig. 2 is a fragmentary front elevational view of the switch and blowout device shown in 'Fig. 1;

Fig. 3 is a sectional view taken substantially on line 3-3 of F18. 1;

Fig. 4 is a vertical sectional view on line l-l of 1'18. 2;

Fig. 5 is a side elevational view of the blowoutdevice with the chute removed;

Fig. 6 is a top plan view of the parts shown in Fig. 5, and

Fig. 'l is a perspective view of certain of the parts illustrated in Figs. 5 and 6.

F18. lillustrates the blowout device in connection with an electromagnetic contactor mounted upon a vertically arranged insulating panel I and provided with cooperating stationary and movable contacts 2 and 3 (Fig. 4) and an operating magnet l. Magnet 4 includes a magnet frame I fixed to panel i, an operating winding I mounted upon a core member 1 associated with said magnet frame, and. a movable armature member I pivotally mounted upon a pin 8 carried by said frame. Armature member 8 is biased to move outwardly with respect to core member I, such movementv being limited by an arm I. thereon which cooperates with a stop surface on the under side of magnet frame 5. Movable contact 3 is fixed to a rocker arm I I which is pivoted upon a pin i2 mounted adjacent the upper end of armature 8. Rocker arm II is provided with a stop projection H which is normally held against the upper end of armature 8 by a spring l5 held under compression between a shoulder a terminal element 20 fixed to panel i throughthe medium of a blowout coil associated with the blowout device.

The blowout device includes a pair of stationary arc horns 22 and 23, the former being mounted upon panel I and having stationary contact 2 fixed thereto, and the latter being asso-' ciated'with the movable contact 3 and being carried by an arc chute 2|. Said blowout device also includes a blowout coil 25 having a pair of pole plates 26-26 associated therewith which are fixed to opposite sides of are chute 24.

More specifically arc horn 22 comprises a U-shaped member the ends of which abut the face of panel I.

i by a bolt 21 (Fig. 3) and stationary contact 2 is fixed to the front end of arc horn 22 by a screw 28. The upper side of said arc horn provides an arc dissipating surface 29 which extends upwardly and rearwardly from said stationary contact and terminates adjacent the face of panel I. Are horn 22 also has curved rib projections 30-40 v on opposite sides thereof which as hereinafter .set forth cooperate with side shields of arc Arc horn 22 is secured to panel in pole plates 20.

panel I by bolts 34. Coremember 32 is insulated from blowout coil 23 by an insulating sleeve 35, and said core member also carries insulating washers 3l3i which are spaced with respect to brackets 33-33 to provide spaces for receiv- The inner ends of pole plates 20 are recessed as shown at 31 in Fig. to receive core member 32 and said pole plates project forwardly to embrace the-region adjacent and above the tips of contacts 2 and 3.

Arc chute 24 is formed of material such a asbestos board and is provided with side shields 33-33 which are secured to opposite sides of a horizontally arranged top shield 39 bybolts 40. Said side shields are shaped to fit over the rib projections 33 on opposite sides of arc horn 22 and are provided with circular openings for receiving inserts 4i which are located on opposite sides of contacts 2 and 3 and are formed of material such as "Carbofrax," or other are resisting material. Top shield 39 is spaced with respect to the upper side of arc horn 22 and the rear end thereof and also the rear ends of side shields 3| abut the front face of panel I to provide an air pocket 42 of relatively small cross sectional area at the rear end of the arc dissipating surface 23.

Arc horn 23 is arranged in front of movable contact 3 and is shaped to provide an elongated arc dissipating surface 43 which is spaced with respect to the side shields 33 and extends upwardly and rearwardly from the front ends of said shielck. The inner end of arc horn 23 is provided with a tip 44 of increased width which abuts the inner faces of inserts 4| and is located above and adiacent the tip of movable contact 3 and the under side of said are horn is proto hold shanks 52 of nuts I against the bottoms of recesses I3. Also when the are chute 24 is in operative position the projections II on the front ends of brackets 52 yieldingly sase the conductor strip 41 and the reinforcing strip 4. which are located on opposite sides of said chute. The upper and lower edges of the recesses 31 in pole plates 23 are substantially concentric to the axis of the rear bolt 42 of arc chute 24, and said are chute can thus be swung upwardly into a position shown in dotted lines in I'll. i to disengage said pole plates from core member 32. As is apparent, arc chute 24 can then be removed by lifting the same upwardly into a position wherein the shanks 32 of nuts II clear the recesses 56 in brackets 53. The left hand bracket 53 (Fig. 2) is electrically connected to terminal element It by a lead 53, and as hereinbefore set forth terminal element It is permanently connected to movable contact 3 by a flexible lead l8. It is thus apparent that when the arc chute 24 is in operative position are horn 23 is electrically connected to the movable contact 3 through the medium of conductor strip 41. The operation of the aforedescribed switch and blowout device is as follows:

Upon energization of winding 6 movable contact 3 engages stationary contact 2 to establish circuit between terminal elements I! and 2'. such circuit including the arc horn 22 and blowout coil 25. Energlzation of blowout coil It establishes a magnetic field and a large portion of the magnetic flux of said field is concentrated vided with a projection 45 which abuts the inner faces of side shields 28. Are horn 23 is secured between the side shields 33 by screws 43 which pass through openings in said shields into tapped openings in projection 45. The screws 46 on one side of are born 23 serve to electrically connect said are horn to a flat conductor strip 41. As shown in Figs. 1 and 2 conductor strip 41 is arranged on the left hand face of arc chute 24 and extends upwardly adjacent the front end of said chute and rearwardly along the upper edge thereof. Conductor strip 41 is secured to are chute 24 by the bolts and said bolts also serve to secure a flat reinforcing strip 43 to the right hand face of saidchute. Pole plates 2| are secured to the outer faces of side shields 33 by screws 32 (Fig. 3) and the front ends of said pole plates overlap the inserts 4! to clamp the same against opposite sides of tip 44 on are horn 28.

One of the bolts 40 associated with arc chute 24 is located adjacent the rear end of said arc chute and has nuts 5| (Fig. 6) on opposite ends thereof each of which is provided with a cylindrical shank I2. The shanks 32 of nuts Hinterlock with a pair of brackets 53-83 which are secured to the face of panel I by bolts l4 and are arranged on opposite sides of arc chute 24. As shown in Fig. 7 each of the brackets I3 is provided with a forwardly projecting arm I! having a recess 56 in the upper edge thereof and a tapered projection 51 on the front end thereof. The shanks 52 of nuts 5| engage within the recesses 58 in brackets 53 to provide a hinge support for the arc chute 24 and as is apparent from Fig. 1 when said are chute is in operative position a core member 32 of blowout coil 25 engages within the recesses 31 in pole plates 25 by the pole plates 28 in the region within the contacts 2 and 3 and immediately above the tips thereof. Upon deenergization of winding 3 contact 3 moves out of" engagement with stationary contact i and at the instant the surfaces of said contacts disengage an arc is formed them between. The relative direction of the current conducted by the arc and the direction of the magnetic flux in the field produced by blowout coil 25 is such that the arc is caused to move upwardly and when the arc reaches the upper tips of contacts 2 and 3 it is transferred to are horns 22 and 23 and passes between the are dissipating surfaces 29 and 43. After the arc is moved upwardly and between the arc dissipating surfaces 29 and 43 contacts 2 and 3 are no lonler in circuit and current is supplied to the are from terminal element is which as hereinbefore stated is connected to are horn 23 throu h the medium of conductor 58 and strap 41. When the arc is transferred to are horns 22 and 23 the same continues to move u wardly and one end of said are travels rearwardly over the arc dissipatin: surface 29 while the opposite end thereof travels forwardly over the arc dissipating surface 41. During such movement of the arc the same is continually elongating and is rapidly cooled bv the surrounding air and the arc horns 22 and 23 which are of hi h thermal conductlvitv and of large heat capacity. When the rate of dissipation of ener y from the arc exceeds the rate of energy supplied thereto the arc is extinguished In p actice it has been found that the pocket 42 at the rear end of arc chute 24 prevents the are from traveling to the rear end of the arc dissipating surface 29. It has also been foulrlr. that spacing of the are surface 43 with respect to the side shields 38 of the arc chute tends is marl'lifan the are away from said side shields 33.

a we 0 aim as new and desir secure by Letters Patent is: e to l. The combination with a vertically arranged etationary con:

insulating panel having a switch mounted upon the front face thereof, said switch having a stationary contact and a cooperating movable contact, a blowout coil having a horizontally arranged core member associated therewith which is fixed to the front face of saidl'panel, an arc chute mounted upon said panel and including spaced side shields arranged on opposite sides of said contacts, each of said side shields having an opening therein located adjacent said contacts, Carbofrax inserts located ciated with opposite ends of said core member and secured to the outer faces of said side shields, said pole plates overlapping said inserts to hold the same in place within the openings in said coil shields.

2, The combination with a vertically arranged insulating panel having a switch mounted upon the front face thereof, said switch including a stationary contact and a cooperating movable contact, an insulating blowout chute having spaced side shields located on opposite sides of said contacts, an arc horn mounted betweensaid side shields and associated with said movable contact, a conductorfixed to the outer face of one of said side shields and electrically connected to said are horn, and a support for said are chute fixed to said panel and electrically connected to said movable contact, said support and said are chute having interlocking parts which are releasable to permit removal, of said are chute, and said. support .also having a part for yieldingly engaging said conductor to electrically connect said are horn to said movable contact w en said are horn is in operative postion.

e combination with a vertically arranged lg panel having switch mounted upon the front face thereof, said switch having a and a cooperating movable contact, a coil having a horizontally arranged core member associated therewith which is fixed to the face of said an arc chute mounted upon said panel and including spaced side shields arranged on opposite sides of said contacts, each of said side shields having an opening thereinlocateol adjacent said contacts, inserts formed of heat resisting refractory material located within the openadjacent to the front face of said panel, said support including interlocking hinge parts secured to said panel and said arc chute which are disengageable upon upward bodily movement of said are chute out of operative position, and

a pair of pole platessecured to the outer faces of said side shields and interlocked with opposite ends of said core member ,to prevent disengagement of said hinge parts, said pole plates being disengaged from said core member upon upward pivotal movement of saidwhute, and said hinge parts being then disengageable for removal of said chute.

5. The combination with a vertically arranged insulating panel, a switch mounted upon the front face of said panel and including a stationary contact and a cooperating movable contact,

a forwardly extending arc horn secured to the front face of said panel and having said stationary contact fixed to the front end thereof,

said are Horn having an elongated arc dissipat' ing surface extending upwardly and rearwardly from said stationary contact and terminating adjacent the front face of said panel, an insulating arc chute extending forwardly from the front face of said panel and having spaced side shields located on opposite sides of said contacts and a top shield arranged above said arc dissipating surface and spaced with respect thereto, a second arc horn carried between the side shields of said chute and associated with said movable contact, said latter arc horn having an arc dissipatingv surface extending forwardly to the front end of said are chute, means for detachably securing said are chute to said insulating panel, and means carried by said are chute and associated with said former means for electrically connecting said second mentioned are horn to said movable contact.

6. The combination with a vertically arranged insulating panel, a switch mounted upon the ings in said side shields, and a pair of forwardly extending pole plates associated 'witlropposite ends of said core member, said pole piates being secured to the outer faces of said side shields and overlapping said inserts to hold the same in place within the openings in said coil shields.

4, the combination with a vertically arranged insulating panel having a switch mounted upon the front face thereof, said switch including a stationary contact and a cooperating movable contact, a blowout coil having a horizontally arranged core member associated therewith which is mounted upon the front face of said panel, an arc chute including verticaiiy arranged side shields located on opposite sides of said contacts, and a horizontally arranged top shield front face of said panel and having a stationary contact and a cooperating movable contact, a forwardly extending are born secured to the front faceof said panel and having said stationary contact fixed to the front end thereof, said are born having an elongated arc dissipating surface extend upwardly andrearwardly from said stationary intact and terminating adjacent the front face of said panel, an insulating are chute extending forwardly from. the front face of said panel and having spaced side shields located on opposite sides of said contacts and a top shield arranged above said are dissipating surface and space-dwith respect thereto, a second arc horn carried between. the side shields of said chute and associated with said movable contact,:

said latter are horn-having an arc dissipating surface which extends forwardly to the front end of said are chute and is spaced with respect to'the side shields of said chute, a support for said are chute including interlocking parts mounted upon said panel and said arc chute, said parts being releasable to permitremoval of said chute, and means carrledby said are chute and associated with said support for electrically connecting said second are horn to said movable contact.

' THEODORE E. JOCHEM.

CLARENCE W, KUHN.

C. STEVENS. 

